This happens when the system runs with no air filter. Outside unit fan doesn't turn but there's a loud hum and a lot of heat coming up through unit. Trane 5 Ton 1625 Seer Two Stage Heat Pump System If the condenser fan motor is receiving the correct voltage but the motor still won’t run, inspect the capacitor to ensure that it is not at fault. Trane ac inside fan not working . We need to check to see if fan is stuck or not. If the coil froze, the fan could be working but the air wont go through the ice until it melts. Difficult to troubleshoot subtle noises from an ac unit from here. When i hit the side of the air handler, fan begins to work in response to the thermostat but when it shuts off automatically, i have to bump the side again to get the fan running. Just cool air blows out the vents. To make sure i'm clear, if ac is set on inside, fans run, some cool comes through vent. The capacitor may have gone bad and therefore the fan won't start...